There are several resources you can use to learn AGK. I'm not sure if I'm able to give a complete list, but you can learn from:
[included examples & code]
AGK comes with quite a lot of examples in the form of working, compilable code that explain how several concepts and commands work.
[the code-snippets forum]
This forum-section is used by forum-members to freely share programs and functions they have created with others. It can also be accessed from your profile-page, where you can use a filter to show AGK-only code.
[online tutorials by Steven Holding]
Fellow programmer and forum-member Steven Holding (a.k.a Baxslash) has
put some tutorials online that should give you a good start.
[online video tutorials]
Several people have put together video's wich the've
put up on sites like Youtube. Quite handy if you like this way of learning.
[AGK-specific books]
There are two good books avaiable that teach you the ins and outs of programming in AGK. They are: '
Hands on AppGameKit Basic' and '
Teach Yourself Game Programming for Android and Windows'. They cost money but are (imho) certainly worth their price.
[interacting with the forums]
The AGK-forums are the central place for asking questions and obtaining new insights. A lot of posts contain a treasure-trove of info and I must say I really like the friendly atmosphere.
There's probably more, but well, this list should give you some pointers on getting started.